Electronically Controlled Warmer Drawer

ABSTRACT

An electronically controlled warmer drawer for food or non-food items having a housing including a heating element based on several heat-producing technologies, temperature and/or humidity sensor(s), and a fan to effectively warm items placed therein. The system is controlled by way of the user interface that interacts with an electronic control system to operate the heating element and fan. The user interface provides user programmable controls and automatic overrides, can be placed in a variety of locations, and can be concealed by a variety of elements. The interface can also utilize a variety of touch sensitive technologies. As well, the device may have a receptacle for adding fragrance or flavor to the objects within.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims a benefit of priority based on U.S. Non-provisional patent application Ser. No. 12/017,895, filed Jan. 22, 2008, the entire contents of which are hereby expressly incorporated by reference into the present application. U.S. Non-provisional patent application Ser. No. 12/017,895 claims a benefit of priority of U.S. Provisional Patent Application Ser. No. 60/886,037, filed Jan. 22, 2007, and U.S. Non-provisional patent application Ser. No. 11/216,443, filed Aug. 31, 2005. The entire contents both applications are hereby expressly incorporated by reference into the present application. U.S. Non-provisional patent application Ser. No. 11/216,443 application claims a benefit of priority of U.S. Provisional Patent Application Ser. No. 60/622,185, filed Oct. 26, 2004, the entire contents of which are hereby expressly incorporated by reference into the present application, and claims a benefit of priority of U.S. Provisional Patent Application Ser. No. 60/606,396, filed Sep. 1, 2004, the entire contents of which are hereby expressly incorporated by reference into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a warming apparatus and, more particularly, to an electronically controlled warming apparatus and an electronically controlled warming drawer.

2. Discussion of the Related Art

Warmer drawers of conventional design are typically configured as closed boxes, having a construction of single wall or a double wall with insulation or air in between and a sliding drawer of some sort to open up the interior of the box. Such conventional warmer drawers often have front door(s) fixed in a vertical plane and heating of the interior has been by a single cal rod (i.e., sheathed heating element) which will radiate heat, thus warming the interior of the box.

The conventional warmer drawers use mechanical controls to control and maintain the food temperatures. These mechanical controls tend to have an undesirable degree of inaccuracy and have a tendency to dry out food, overheat, and have large swings in temperature ranges from a desired set point, which results in over and under shoots.

These sensors and the design of operation generally cause slow response for temperature corrections, thus causing temperatures to over shoot and under shoot. These resulting temperature ranges and swings, from the on to off cycling, have a tendency to drive moisture out of foods, hold more moisture in the chamber, and/or over cook food(s). Also, when set for the proofing temperature, bread will not proof correctly (i.e., not to rise properly) at lower temperatures, and at the higher temperatures bread tends to develop large pockets of air.

Conventional warmer drawer designs typically use knobs and slides to set and control mechanical switches for setting the desired temperature. However, these mechanical switches are generally known to be inaccurate in their setting and repeatability. The mechanical switches often have problems maintaining a set point and can permit swings in temperature within the chamber partly due to the design of the warmer drawer and method of heating, but also due to the inaccuracy of the mechanical switches themselves. The inaccuracy of the mechanical switches tends to increase the effects of having temperature over and under shoots and contributes to the large temperature swings inside the chamber of the warmer drawer. This inaccuracy is believed to contribute greatly to the gradient temperature problems found in present warmer drawers with the chamber having problems with temperature over shoot and under shoot.

The mechanical switches typically used in conventional warmer drawers are also susceptible to the adverse effects of surrounding environmental influences. For example, if subjected to cold temperatures, mechanical switches could work slowly, crack, become hard to turn, fail to operate, their lubrication can harden causing the operation not to function, cause switch chatter resulting in premature failure or reduced life of product, and cause other detrimental issues to a user. Typical mechanical switches and controls for conventional warmer drawers tend to have poor repeatability and generally do not provide the user the ability to repeatably return to a certain preset position (e.g., reuse of same settings, etc.) or reliably establish the same temperature when using the conventional warmer drawer in a series of different operations. For example, a user generally cannot set a proper temperature on one day and then return the next day to the same set point if the controls were moved during an intervening period (as is often necessary). Temperature swings of as much as 30 degrees or more are believed to occur in such instances.

The conventional warmer drawers are also subject to other deficiencies. For example, conventional warmer drawers are typically constructed for use in permanent (e.g., built-in, etc.) installations, such as to cabinetry, an appliance, or some other generally stationary structure. Examples include conventional warmer drawers built into a cabinet under a product such as a cook top, oven, or some other appliance like a slide-in stove to a drop-in range. In other applications, conventional warmer drawers can be used in a location independently, but are still typically built into a cabinet or some structural frame. This limits the mobility of the warmer drawer from being used in a variety of desirable locations. Accordingly, it would be desirable to provide a warmer drawer capable of being used as a freestanding unit, as a mobile unit, used under a cabinet (e.g., suspended), or in areas with or without the support from a structural frame.

Therefore a need exists for a warmer drawer in which more accurate and controlled heating of objects such as food is accomplished. There also exists the need for an accurate method of controlling the operations and settings of the warmer drawer. There also exists a need for the controls of the warmer drawer to be less susceptible to environmental influences. There also exists a need for a display device to permit a user to be able to view/see the operation, temperature indication(s), set point functions, and view of the contents of the chamber. There also exists a need for a warmer drawer capable of remote control operation. There is a further need to accurately apply and control heat within the chamber of the warming drawer. There is also needed for a warmer drawer such that it can be used in any desirable location to suit the particular needs of a user.

Accordingly, it would be desirable to provide a warming apparatus, such as a warmer drawer having electronic control, with any one or more of these or other advantageous features.

SUMMARY OF THE INVENTION

One object of this invention is to provide a warming apparatus that has one or more of the characteristics discussed below.

The present inventive warmer apparatus for either indoor or outdoor use consists of an enclosure defining a chamber with a heating element. A sensor system, preferably comprising at least one sensor, is operably coupled to the chamber and sends signals to an electronic control system that is operably connected to the heating element and a user interface provided on the enclosure or faceplate. A drawer is provided and is extendable from the chamber of the warmer and a means for preventing fluids and other contaminants from entering the chamber is also provided for between the enclosure and the user interface and drawer.

The user interface, for example, an electronic control panel, can be installed raised, recessed, or flush with the enclosure and can be constructed out of glass, plastic, metal, rubber or a composite material. The touch panel is preferably sealed and/or coated to protect the electronic controls from being damaged by the elements and to prevent fluids, insects, and other contaminants from gaining entry to the chamber through the touch panel. The touch panel may also include decorative overlays, labels, and trims that are configured for outdoor use. The touch panel may be mounted on the faceplate of the warmer or elsewhere on the enclosure and may be disconnected from the enclosure and used remotely by a wired or wireless controller. In another embodiment, the user interface uses one of a tactile, membrane, piezoelectric, capacitance, resistance, induction system, touch panel, or keypad for the selection of various operations.

The warmer preferably includes a fixed or variable speed fan that is located either in the chamber or remotely. Again, it may also be attached to the heating element or independent of it. The fan is used for mixing air, removing air, or controlling the moisture within the chamber of the warmer.

The warmer can be used for non-food or food and drink items alike. Flavoring additives may be added to the chamber so as to impart various flavors or scents to the items being warmed within the warmer.

The inventive warmer may also include a timer control that may be programmed by a user to automatically turn off the warmer after a certain amount of time. The warmer may also be capable of preset temperatures, preset times, and preset operations.

The warmer's user interface may be configured to display the current time, operations, temperatures, functions, remaining time, diagnostics, features, fan speeds, alarm controls and signals, messages, timed on/off, time delay or be remotely controlled by voice or sound commands from the user.

The warmer may also comprise accessible panels or walls on either its front, side, top, back, or bottom so that a user may gain access to the chamber of the warmer. Furthermore, the warmer may comprise additional warming chambers, e.g., one for food and one for non-food items.

According to one aspect of the present invention a warmer drawer is provided having a housing with a cavity, an extendable portion slidably connected to the housing that fits within the cavity, a door connected to the extendable portion, a heating element located in the cavity, a fan for moving heated air within the cavity, electronic controls for operating the fan and the heating element, and a sensor in communication with the electronic controls for controlling the current supplied to the heating element. Thus it is one object of the invention to provide a drawer for easy access to a warming chamber that effectively heats the items in the drawer under the user's control.

According to another aspect of the present invention, the warmer drawer may also have a panel configured to conceal the electronic controls, which may be a sliding panel, a sliding spring-biased panel, a sliding panel display, a panel on a rotating element, a L-shaped plate, a matching panel, and a portion of a rotating element having at least one electronic control. As well, there may be a cabinet where the panel is located on at least one extendable portion of the cabinet. Thus it is another object to provide an attractive warmer drawer by allowing the electronic controls of user interface to be concealed.

In yet another aspect, the invention's electronic controls may include programmable settings such as on/off settings. The programmable on/off settings may have automatic shutoff with an infinite setting of the automatic shutoff to disable the automatic shutoff. It is thus another object of the present invention to provide several useful features, including for safety and convenience, to allow the user to control the operation of the warmer drawer operation.

In still another aspect of the present invention the warmer drawer may have a receptacle for receiving aromatic materials wherein the aromatic materials are one or more of a fragrance source, flavoring additives, wood chips, and liquid smoke. Thus, it is an object to provide flavor and fragrance to objects in the drawer as well as warming.

In yet another aspect of the present invention, the warmer drawer heating element may be a convection heater, a cal rod, a heat plate, a glass film, a thermal ceramic heater, a flexible heater, a light, an infrared device, an inductive device, an electromagnetic device, a radio frequency device, a heat pump, a warming liquid device, a heat exchanger, an axial fan heater, a sonic heater, a gas fuel product, a solid fuel product, a radiant heating device, and/or a microwave device. It is thus yet another object to provide for a warming drawer having effective heating technology.

In still another aspect, the warmer drawer's electronic controls have an electronic display touch control panel with input elements that respond to user input. The operating technology of the input elements may of piezo electric, capacitive, resistive and infrared. In addition, the electronic controls may located in a variety of locations with respect to any plane on the drawer assembly and/or door, for example, at a location that is flush, raised, recessed, and may be recessed beneath glass, plastic, or composite material. It is thus yet another object to provide for a warming drawer having effective, attractive, and accessible electronic control input technology.

In anther aspect, the warmer drawer may also have an upper chamber and/or a lower chamber wherein the fan is located in one or both. Thus, it is another object to provide for a warming drawer that effectively heats the objects within the chamber.

In another aspect of the present invention the warmer drawer electronic controls may be on the drawer assembly and/or the door. Furthermore, the electronic controls may be concealed by moving the drawer assembly to a closed position. Thus, it is another object to provide controls that are easily accessible during the use of the warmer drawer that may be concealed when the drawer is closed for improved appearance.

In still another aspect of the present invention a method of manufacturing a warmer drawer has steps of defining an enclosure with a chamber and having an opening, configuring a movable portion to be moved with respect to the chamber, providing a heating element to heat to the chamber, configuring a user interface to receive input from a user for controlling operation of the warmer drawer, providing a sensor to sense a signal representative of a temperature of the chamber, and configuring an electronic control system for interfacing with the heating element, the user interface and the sensor to control a supply of electrical power in a continuous and regulated manner to the heating element during operation of the warmer drawer. The movable portion may be a lid, a drawer, or a door. Thus it is still another object to provide for a method of manufacturing a warmer drawer configured for usage in a flexible variety of uses.

In another aspect, the method of manufacturing a warmer drawer may also include the step of providing a second sensor such as a humidity sensor and/or a temperature sensing device. The second sensor may be a thermostat, a thermal protector, a thermal cutoff, a thermal switch, a thermocouple, a PCB thermostat, a time delay relay, a bulb and capillary device, a cold control, a bimetallic device, a pressure switch, a resistance temperature detector, a snap action switch, and/or a thermistor. Thus, it is another object to provide a method of manufacturing that produces a warmer drawer that can additionally sense humidity or sense temperature in more than one location to accurately monitor the condition of the objects in the drawer.

In still another aspect, the method of manufacturing a warmer drawer may also include the step of connecting the user interface having a display device configured to provide information to a user. The display device may use a display panel having technology such as light emitting diodes, a liquid crystal display, a plasma, a dot matrix, and/or a vacuum fluorescent display. The method may have an additional step of providing an element configured to hide the user interface such as a sliding panel, a sliding spring-biased panel, a display that is substantially similar to a surrounding surface, a panel on a rotating element, and/or a portion of a movable element having at least one electronic control. Thus, it is still another object of the present invention to provide a user display device that may alternatively be hidden from view to improve the warmer drawer aesthetics.

In yet another aspect, the method of manufacturing a warmer drawer may also include the step of providing the user interface that includes has one or more set points, timers, temperatures, on/off settings, automatic shutoff, and/or an infinite setting override of an on/off timer. Thus, it is another object to manufacture a warmer drawer having programmable features for ease-of-use.

In yet another aspect, the method of manufacturing a warmer drawer may also include the step of providing a receptacle for a source for fragrance, and/or a source for flavoring. Thus, it is an object to a method of manufacturing a warmer drawer that provides flavor and/or fragrance to objects in the drawer.

In yet another aspect, the method of manufacturing a warmer drawer may also include the step of providing a user interface comprising a touch screen having at least one input element configured to respond to a user input wherein the touch screen may have input element(s) that are displayed in response to a user input. The touch screen operating technology may be piezo electric, capacitance, inductive, resistance, infrared, magnetic, field effect, charge transfer, hall technology, and/or high frequency. Thus, it is one object to the method of manufacturing of a warmer drawer to provide an interactive and useful touch screen that may respond to the user input by displaying one or more input element(s)

These and other aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode currently contemplated of practicing the present invention.

In the drawings:

FIG. 1 is a perspective view of one embodiment of the warmer drawer of the present invention;

FIG. 2 is a fragmentary enlarged view of a portion of the warmer drawer of FIG. 1;

FIG. 3 is fragmentary enlarged view of another portion of the warmer drawer of FIG. 1;

FIG. 4 is fragmentary enlarged view of another portion of the warmer drawer of FIG. 1;

FIG. 5 is fragmentary enlarged view of another portion of the warmer drawer of FIG. 1;

FIG. 6 is fragmentary enlarged view of another portion of the warmer drawer of FIG. 1;

FIG. 7 is an exploded view of the warmer drawer of FIG. 1 with sections removed to show flow;

FIG. 8 is a sectional plan view taken along the lines of 8-8;

FIG. 9 is a fragmentary enlarged view of the area along 9-9;

FIG. 10 is a perspective view of a second embodiment of the warmer drawer of the present invention;

FIG. 11 is a sectional plan view taken along the lines of 10-10;

FIG. 12 is a schematic of an electronic control circuit for use with the present invention; and

FIG. 13 is a schematic of another electronic control circuit for use with the present invention.

FIG. 14 is a side elevation view of an exemplary embodiment of a warming appliance including an electronic controller to control the temperature, humidity, power and other user defined parameters shown with a drawer extended from an enclosure.

FIG. 15 is a top plan view of a warming appliance according to the embodiment of FIG. 14.

FIG. 16 is an illustration of an exemplary embodiment of a heating apparatus in a warming appliance.

FIG. 17 is a side elevation view of a warming appliance with a drawer in a closed position and illustrating an exemplary embodiment of a user interface, power circuit, and an electronic control device.

FIG. 18 is a block diagram of an exemplary embodiment of a power circuit for a warming appliance having an electronic controller and including a humidity control circuit and other sensors.

FIG. 19 is an exemplary embodiment of a fan/heater apparatus for use with a warming apparatus.

FIG. 20 is an alternative exemplary embodiment of a fan/heater apparatus for use with a warming apparatus.

FIG. 21 is a schematic diagram of an exemplary embodiment of an electronic control circuit for a warming appliance.

FIG. 22 is a schematic diagram of an exemplary embodiment of a power circuit for a warming appliance, including a temperature sensor and circuit.

FIGS. 23A-23B are elevation views of an exemplary embodiment of a warming appliance, including a venting system illustrating proportional venting to control heat and air flow in the warming appliance.

FIG. 24 is an illustration of a venting system for a warming appliance with an actuator to selectively operate the vent to control heat and air flow according to an exemplary embodiment.

FIG. 25 is an illustration of a venting system for a warming appliance with another actuator to selectively operate the vent to control heat and air flow according to another exemplary embodiment.

FIG. 26 is an illustration of a venting system for a warming appliance with a further actuator to selectively operate the vent to control heat and air flow according to a further exemplary embodiment.

FIG. 27 is a perspective illustration of an appliance configured to exchange a storage drawer (shown as the left device) for an exemplary embodiment of a warming apparatus (shown as the right device).

FIG. 28 is an illustration of possible locations of a warming apparatus in relation to another appliance (shown for example as a stove).

FIG. 29 is a side sectional view of an exemplary embodiment of a free standing warming apparatus mounted on wheels for mobility.

FIG. 30 is a perspective view of an exemplary multi-use warming apparatus configured to couple to a stand structure which can be movable, as facilitated by several alternative devices.

FIG. 31 is a sectional view of an exemplary embodiment of a warming appliance illustrating several locations of light fixtures mounted in the chamber.

FIG. 32 is a detailed view of a mechanical door switch for operating the light fixtures of the warming apparatus illustrated in FIG. 31.

FIG. 33 is a detailed view of an electronic door switch activated with a magnet for operating the light fixtures of the warming apparatus illustrated in FIG. 31.

FIG. 34 is a partial perspective view of an exemplary embodiment of a face plate of a warming apparatus including an “on/off” type user interface.

FIGS. 35A-35E are illustrations of exemplary embodiments of a user interface for a warming apparatus.

FIG. 36 is a perspective view of an exemplary embodiment of a multi-use warming apparatus associated with another appliance (shown for example as a cook top) and controllable remotely with a remote control unit.

FIG. 37 is a perspective view of an exemplary embodiment of a multi-use warming apparatus having a removable remote control unit coupled to the face plate of the warming apparatus.

FIGS. 38 and 39 are detailed views of an exemplary embodiment of a coupling method of the user interface to the warming apparatus illustrated in FIG. 37.

FIG. 40 is a sectional side view of an exemplary embodiment of a warming apparatus coupled to a remote heater/blower.

FIG. 41 is a partial perspective view of an exemplary embodiment of a warming apparatus illustrating alternative venting from the chamber (arrows depict an exemplary air flow pattern).

FIG. 42 is a side view of the venting illustrated in FIG. 41.

FIG. 43 is a partial side sectional view of an exemplary embodiment of a warming apparatus including a depository for a fragrant substance in gaseous communication with the drawer of the appliance.

FIG. 44 is a side sectional view of an exemplary embodiment of a multi-use warming apparatus, including a powered drawer.

FIG. 45 is a detailed view of an exemplary embodiment of the warming apparatus with a powered drawer illustrated in FIG. 44.

FIGS. 46 and 47 are alternative embodiments of a warming apparatus illustrating coupling and motion of a door (or panel) for accessing a chamber of the warming apparatus.

FIGS. 48 and 49A-49E are schematic views of a movable display device and user interface according to an exemplary embodiment.

In describing the preferred embodiment of the invention that is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. For example, the word “connected,” “attached,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, attachments, couplings, and mountings. In addition, the terms “connected,” “coupled,” etc. and variations thereof are not restricted to physical or mechanical connections, couplings, etc. Such “connection” is recognized as being equivalent by those skilled in the art.

Further, before any embodiments of the invention are explained in detail, it is to be understood that the invention is capable of other embodiments and of being practiced or of being carried out in various ways. Further, the use of “including”, “comprising”, “at least one of”, or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments described in detail in the following description.

1. SYSTEM OVERVIEW

The present invention is preferably an appliance or device, for example, including an electronically controlled warmer having an enclosure with sides, e.g., a top, bottom, front, back, left and right walls, a chamber, drawer, door, user interface, faceplate, at least one heating element, a venting system, fan, sensor or detection system, electronic control system, and environmental seals.

As described herein, the warmer or warming drawer preferably comprises a heating element such as an electric PTC (Positive Temperature Coefficient) ceramic heater. However, more than one heating element may be used. Alternatively, other heating elements may replace or be used in conjunction with the PTC ceramic heater in the warmer drawer. Other potential heating elements that may be used include: convection heaters, calrods, wire heating elements, heat plates, glass film, thermal ceramic heaters, flexible heaters, lights, infrared, inductive, electromagnetic, and radio frequency devices, heat pumps, warming liquids, heat exchangers, axial fan heaters, sonic heaters, and gas and solid fuel products. Electronically controlled heating methods such as radiant, infrared, conduction, inductive, convection, resistance and microwave methods may also be used.

A user interface is provided on the warmer drawer for control by the user. As further described below, the interface may include an electronic touch panel designed to control the heating elements. Alternatively, knobs, slides, or switches may be used. The user interface can be, for example, piezoelectric, capacitance, tactile (membrane switches), resistance type, padless touch soft switch technology, padless touch digital encoder, infrared frequency dependent, magnetic switches, field effect, charge transfer, Hall Effect, micro encoder, infrared, high frequency, inductive computer key board, computer screen, sound, radio frequency, or induction touch panel (keypad) for use by the operator. Such controls can be installed on the warmer flush, recessed, or raised and coupled. Electronic controls can be placed on any surface so as to accommodate any design for matching other products.

In the embodiment shown, the controls are recessed within a faceplate located on the warming drawer enclosure to permit a door to be closed flush with the faceplate. Such a control, e.g., electronic touch panel, may be made of glass, metal or plastic with selection of the operating function(s) made by touching the surface of the glass, metal, plastic or of other substrates to operate the warming apparatus. The panel may also have membrane, tactile, resistance, and/or capacitance switches with decorative overlays, labels, and trim. Touch control keypad panels can be installed flush, raised, recessed, or remotely on any plane with the use of electronics. Remote control can be by wire or by wireless means so that the electronic controls may be placed on any surface to accommodate any design or for matching other products. Any of these types of user interfaces may be fitted with decorative overlays, labels, and trim so as to interface with the user.

The use of electronics is disclosed herein. For example, these include micro-controllers, microprocessors, integrated circuits and drivers, PC Boards, processors, and power circuits may be used to better control functions, operations, and temperatures and may be factory preset so as to limit the user to simple on and off operation of the unit. The overall size, design, look, and feel of the warmer can be matched to the size, design, look, and feel of any appliances associated with the warmer.

Electronic controls are generally sealed better than mechanical controls, and therefore electronic controls are less susceptible to degradation when exposed to the elements. Electronics also reduce the unit size so that the inventive warmer may now be used in a number of places where present units cannot.

The electronic controls described herein may be configured to allow for timed on/off control based on one or more sensors or controls such as temperature, moisture control, electronic sensors, programmable/selectable set point(s), programmable/selectable set time(s), programmable/selectable set operation(s), and programmable/selectable set temperature(s).

The use of electronics provides for better control and offers more operations than can be had in a mechanically controlled device. The warmer may also be configured with factory preset operations, functions, and temperatures.

The warmer drawer preferably includes an electronic control system operably coupled with the user interface and the heating element. The electronic control system preferably will control the heating element in response to a signal from the user interface so that the operator may be able to maintain the appropriate temperature within the chamber.

The electronic control system described herein is designed to better regulate the electrical current supplied to the heating element. By improving the accuracy of the current supplied to the heating element, control of the heat output to the chamber is improved, and thus the accuracy of the temperature in the chamber is also improved. By improving the accuracy of the temperature within the chamber, the quality of, for example, food items in the warmer is also improved. PTC sensor technology is one method for controlling or regulating the current supplied to the heating element. PTC technology provides better control over the current supplied to the heating element and thus greatly reduces the need to continuously cycle power on and off to regulate temperature. As such, temperature over and undershoots are greatly reduced, and the time required to heat the chamber to the proper temperature is also reduced. PTC technology is but one method of controlling the current supplied to the heating element, and it should be noted that other methods are contemplated.

The electronic controls may also be coupled by a system that protects the electronic controls in the case of a malfunction. One example of such a system is the watchdog timer, which is a timer counting cycles of a separate on-chip 128 kHz oscillator. The watchdog gives a system reset when the counter reaches a given time-out value. In normal operation mode, it is required that the system uses the Watchdog Timer Restart (“WDR”) instruction to restart the counter before the time-out value is reached. If the system doesn't restart the counter, a system reset will be issued. The system reset from the watchdog gives a reset when the timer expires and is used to prevent system hang-up in case of runaway code or other malfunction preventing program operation. The reset condition reinitializes the system hardware and software from the beginning. Inputs and outputs are default inputs (high-impedance) after reset, until configured by the same program that is periodically restarting the watchdog. This prevents outputs from driving off-chip circuitry under persistent conditions causing reset from the watchdog.

A fan is also disclosed herein. In general, the fan is for circulating heated air throughout the upper and lower chamber and controlling humidity build-up. The fan may be used with or without a heating element attached to it. It can be secured to the inside of the upper chamber or remotely located but in fluid communication with the warmer. The fan may preferably be used to circulate air to provide better heat control and response time. By circulating air, hot spots or stratified layers of varying temperature within the chamber are eliminated. Improvements to the cavity temperature help to eliminate the temperature swings inside the chamber, thus providing better control and eliminating the need for user control. The fan may be a fixed or variable speed fan.

A motorized, electromagnetic, solenoid, powered or non-powered venting system may also be provided. The venting system is preferably configured to optimally control the temperature, humidity, and airflow of the chamber. Sensors or a system of sensor may be utilized to determine the humidity or temperature in the chamber and to send a signal to the venting system's electronic control system reporting the sensed humidity or temperature. The venting system, in response to a signal from the electronic control system, may open or close the vents to regulate the conditions within the chamber. The venting system may further comprise mechanical louvers, slots, apertures, closures, or holes for controlling the moisture in the chamber. The venting may be located in the back, bottom, ceiling, walls, or front faceplate.

The sealing means may also include gaskets, adhesive tape, double sided tape, RTV, glues, epoxies, silicon gels, foam, rubber shapes, and other materials. Welding may also be used to seal the warmer. The device preferably has at least one weather-tight seal between the door and the frame preventing environmental contaminants from entering the chamber and/or damaging any of the electronics located within the device. Seals may be located anywhere else on the device where there may be gaps present that would allow fluids or other environmental contaminants from entering the chamber.

Additionally, sealing of the electronic components and user interface is accomplished with coatings, for example, that cover the electronics, electronic boards, and or other components.

One or more sensors for the warmer are also described. These may be used to sense various environmental conditions. In one embodiment, a sensor scans the warmer for an item placed therein. It may also provide feedback to the device's electronic control system to operate a fan. Sensors for the appliance may be also used to detect at least one of: airflow, smoke, temperature, speed, power, resistance, voltage, programmed operations, and set points. The use of sensors and sensor systems will allow for more control over the environment inside the chamber, thus regulating and maintaining proper temperature and humidity levels. Maintaining proper temperatures can prevent food objects placed in the warmer from drying out. Additionally, non-food items placed in the drawer, such as towels, can benefit from being stored at the proper temperature and humidity levels.

In one embodiment, a scanning infrared detection system could be placed in the upper chamber of the warmer to detect the temperature of the contents of the chamber. In one embodiment, thermopile (pyrometry) and thermopile infrared sensors are used. Various other sensors could be used, but are not limited to, those such as a thermostat, thermal disk, thermal protector, thermal cutoff, electronic temperature controller/sensors, electronic/mechanical AC or DC sensor/control devices, temperature sensors, thermal switch, thermal couples, bulb and capillary, electronic controls, bimetallic, pressure switches, creed action thermostats, resistance temperature detectors, controllers, manual resets, automatic resets, disc thermostat, snap action switch, negative temperature coefficient of resistance thermistors, and power positive temperature coefficient of resistance thermistors.

The warmer described herein preferably has a movable drawer assembly that can be constructed in a number of different ways. For example, the drawer can use guide members coupled to the chamber of the device for retracting and extending the drawer. The guide members are connected to a movable frame that facilitates the retraction and extension of the drawer. Alternatively, one could use slides, glides, formed grooves, rollers, ball bearings, bearing pads, or other methods of guiding the drawer into the chamber. In another embodiment, the drawer can be directly coupled to the guide members without the use of movable frame. In this embodiment, the drawer is simply placed in and out of the warmer by mounting the drawer assembly on opposed angle slides. The drawer may be operated with a control and powered drive or may be manually operated.

The enclosure described herein preferably comprises a frame, front, back and two side vertical panels, an upper panel and a bottom panel. The drawer assembly comprises a frame having a back panel, bottom panel, front faceplate panel and a plurality of towel bars mounted to the back panel and front faceplate.

The front faceplate panel can be constructed so as to match the surrounding appliances or cabinetry. The door front is preferably designed to channel any fluids or other environmental contaminants away from the device. In the preferred embodiment, a positive lock closure helps hold the drawer assembly to the enclosure.

The device is preferably made with high-heat construction so that it can safely be installed into or along side cabinets or walls constructed of wood or other materials susceptible to degradation when coming into contact with heat. The device can also be constructed so that it is a freestanding or standalone unit not requiring a structural frame or cabinet. Preferably, the device is constructed of a material resistant to chemicals, high and low temperatures, ultraviolet rays, fluids, and insects.

The device preferably consists of a warmer with a lighting element located inside the chamber to provide illumination. The lighting element is preferably configured to illuminate upon opening and/or upon the turning on of a switch. The lighting element can consist of any type of lighting device capable of withstanding the temperatures within the chamber. Because warmers are typically placed low to the ground, it is typically difficult to see the objects inside the chamber. The use of the lighting element will greatly increase the operator's ability to see inside the chamber. This may be aided through the use of glass or transparent doors on the front of the device.

The disclosed warmer may also be equipped with at least one of: a colored, e.g., blue, LED power indicator, on/off rocker switch, a LCD display, an illuminated display that can be adjusted in color and intensity, a plasma display, a dot matrix display, line segment display, and a vacuum fluorescent display may be used for displaying of information such as functions, temperature, humidity, and times.

Programmable set points, times, timers, temperatures, on/off settings, and operations are another aspect of the present invention. The electronic control system, through signals preferably received from the user interface, can operate and control the programmable settings. The use of an electronic control system offers an advantage over a mechanical system where the user would not be able to program such settings.

In one embodiment, the device may have a timed on/off control so that the device is automatically turned off after a predetermined period of time.

In another embodiment, the warmer is configured with factory-preset times, points, operations and temperatures. In this embodiment, the device simply comprises an on/off switch or control and no other user interaction is necessary to operate the warmer.

2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments of the device of present invention are shown in FIGS. 1-49E, which are described in additional detail below. All of these embodiments are configured from the same basic design and like reference numerals refer to like components.

Referring to FIGS. 1-7, a non-food warming appliance 10 (hereinafter also referred to as a “warmer drawer 10”) is comprised of an outer enclosure or housing 12 defining a cavity 14. The enclosure 12 can be made of stainless steel, plastic, coated metal, glass, ceramic or other metal or non-metal materials or combination of such materials and can be of a decorative nature. According to the illustrated embodiments, the chamber is not intended to be airtight, and is provided with suitable passageways (e.g. air inlet, air exhaust, etc.) to foster a desired air flow pattern within the chamber.

As best seen in FIGS. 1 and 7, the warmer drawer 10 includes frame 16, along with a top 18, sides 20, a bottom 22, and a back 24, all which comprise the outer enclosure 12. Single wall construction of the enclosure 12, preferably out of stainless steel, may be used in applications where the surrounding surfaces can accommodate the heat loss. As shown in FIG. 7, a double wall construction with an insulating material or airspace between the walls to minimize heat loss to the external surface of the enclosure 12 may be used.

A partition 26 divides the cavity 14 into an upper chamber 28 and a lower chamber 30. The upper chamber 28 contains a heat source, e.g., PTC ceramic heater 31, a sensor, e.g., thermal limit switch 32, and an air handling unit or fan, e.g., cross-flow blower 34. The ceramic heater 31 is positioned above an air inlet 35. Air flowing into the upper chamber 28 through the inlet 35 passes through the heater 31 when entering the chamber 28. The fan 34 is connected to an upper chamber outlet vent 37 such that heated air flowing through the fan 34 is directed to the lower chamber 30. The fan 34 may alternatively be located in the lower chamber 30 or even remotely from the warming drawer 10 and may be either a fixed or variable speed fan. The fan 34 can be used for at least one of removing air, mixing air, and controlling moisture in the lower chamber 30. In another embodiment, the fan 34 is connected to and works in combination with the heating element 31. Heater 31, thermal limit switch 32 and fan 34 are operatively connected to electronic controls 39.

The lower chamber 30 includes a back plate 36 having a plurality of apertures 38 formed therein. The heated air directed by the fan 34 is blown into a space 40 formed between the back wall 24 of the enclosure 12 and the back plate 36. The air is then forced through the plurality of apertures, or slots, 38 by a difference in pressure to provide a uniformly diffused airflow. Angled support housings 42 for retractable slides 44 are also located in the lower chamber 30. The interior dimensions of the preferred embodiment are eighteen inches wide by seventeen and three-eighths inches high by fifteen and one-half inch deep (18″ W×17⅜″ H×15½″ D).

The warming drawer 10 further comprises a front panel 46 and a drawer assembly 48. The drawer assembly 48 preferably includes a rack 49 having at least one support member, i.e., bracket, hanger or towel bar, 52 for supporting objects thereon. Each towel bar 52 is preferably formed from a sufficiently rigid material in an upside down “V” or triangular shape to “open up” or spread out the objects to be warmed, e.g., towels (see FIGS. 7-9). Furthermore the “V” shape towel bar may permit air to move freely around the objects to be warmed and the cavity, may decrease the time to warm the object, and may help to provide an even temperature distribution for the object to be warmed. Preferably, the towel bars are made of metal which may facilitate heating the portion of the item to be warmed, e.g., a towel that is in contact with the towel bar. The drawer assembly 48 is preferably coupled to the enclosure 12 via movable fixtures such as slide assemblies 44 for movement between a retracted position to warm the objects in the lower chamber 30 and an extended position so that an operator may access the towel bars 52. The drawer assembly 48 further comprises a base plate 56 and a door or faceplate 58. Slots 59 are formed in the rack 49 and aligned in fluid connection with the slots 38 in the back plate 36. Outlet vents, e.g., slots, 60 are formed in the front of the base plate 56 near the face plate 58 to complete the air flow path thereby facilitating air flow over the towel bars 52.

The front panel 46 has an opening 62 formed therein to receive the drawer assembly 48. The front panel 46 preferably includes seals 64 between the drawer faceplate 58 and the enclosure 12. The seals 64 prevent fluids and other environmental contaminants from entering the lower chamber 30. The opening 62 is formed with an upper recessed lip portion 66 to receive the seals 64 and a lower recessed lip portion 68. A number of slots, or inlet vents 70, are formed across the width of the lower lip portion 68 to draw in fresh air, though some heated air from vents 60 may also be drawn in.

The front panel 46 may further comprise an etched logo 72 and an indicator, i.e., blue LED, 74. An electronic control panel, e.g., on/off rocker switch 76, is provided within a small recessed portion 79 and operatively connected to the electronic controls 39. Alternatively, any number of electronic displays could be used, such as an electronic touch panel that can be configured to allow a user to select the desired heating parameters. The logo 72, indicator 74 and switch 76 are covered by the faceplate 58 and hidden from view when the drawer assembly 48 is closed.

As previously mentioned, the drawer assembly 48 comprises two slide assemblies 44 to move the drawer assembly 48 between a retracted and an extended position. A friction lock closure 78 is located on the lower lip portion 68 to latch with a corresponding closure (not shown) to hold the drawer assembly 48 closed.

In operation, the drawer assembly 48 is opened to reveal the support members, i.e., towel bars 52. Non-food objects, preferably textile fabrics including towels 80, are draped over the bars 52 and the warming drawer 10 is turned on via rocker switch 76. The drawer assembly 48 is then closed, i.e., returned to the lower chamber 30. The heater 31 is turned on and automatically begins heating the air in the warming drawer 10. The fan 34 turns on and begins to circulate warmed air from the upper chamber 28 to the lower chamber 30. Warmed air flows through the lower chamber 30 and circulates about the towels 80.

The majority of air is drawn in from the front of the warmer 10 under the moveable drawer assembly 48 through the inlet vents 70 located in the lower lip 68 of the enclosure front panel 46. The air is pulled into a space 33 created from the double wall construction of the warmer 10. A small slot (not shown) between the lower chamber 30 and the space 33 permits an additional, though limited, amount of heated air to flow into the space 33. The mixed air travels up the sides of the warmer 10 through the space 33. The air is pulled into the upper chamber 28, through the heater 31 and into the blower fan 34.

The heated air is then directed back into the lower chamber 30 via the space 40 and through the slots 38 in the back plate 36 and finally into the drawer assembly 48 via slots 59. Due to the opening and spreading of the towels 80 from the towel bars 52, a greater surface area of the towels 80 is exposed and heated by the heated air. After passing through and around the towels 80, the majority of the heated air is vented through the vents 60 in the base plate 56. Some of the heated air is vented through the slot (not shown) and into the space 33 as previously discussed. After a period of time has passed, the door 58 is opened and the drawer assembly 48 is pulled out from the lower chamber 30 via the slide assemblies 44 with warmed towels 80.

Referring now to FIGS. 10-11, a slightly different embodiment of the present invention is shown. As seen in FIG. 10, the warming drawer 110 also includes an enclosure 112 and a drawer assembly 148. The preferred interior dimensions of this embodiment are eighteen inches wide, thirty-five and three-eighths inches high by fifteen and one-half inches deep (18″ W×35⅜″ H×15½″ D).

FIGS. 12-13 show examples of control circuits that may be used with the present invention. These are only examples of preferred control circuits, and the control circuit of the present invention is not limited to those disclosed in FIGS. 12 and 13.

The warming drawer 10 may be installed at any suitable location, e.g., a cabinet or a support platform. It is preferred that the warming drawer 10 be secured at the desired location to prevent the warming drawer 10 from tilting or even falling over when the door is opened. For example, an anti-tip brace could be installed to prevent the warming drawer 10 from tipping forward when it is opened and loaded.

For installation into a cabinet, the following method may be used. First, an installer may position the warming drawer 10 in front of the space into which the warming drawer 10 is to be inserted. Second, the installer may plug the power cord into the desired outlet, ensuring that any excess cord length is positioned so that the warming drawer 10 will not pinch, kink, score or cut the cord when the warming drawer 10 is inserted into the opening. Third, the installer may slide the warming drawer 10 into the space until the face plate of the warming drawer 10 is flush to the surface of the cabinet. At this time, the installer may check the warming drawer 10 to ensure that it is level within the space. Finally, fasteners, e.g., screws, may be used to secure the warming drawer 10 within the cabinet. A wood plank or decorative plate may be used to cover the drawer front. This allows the drawer to better fit into the surrounding environment.

After the warming drawer 10 has been installed, it may be operated as follows. First, the operator may open the drawer of the warming drawer 10. Second, the operator may place the desired items, e.g., towels, into the warming drawer 10. Third, the operator may push the on/off switch to turn on the warming drawer 10, which will then begin to heat the desired items, e.g., towels. After the desired items have been warmed, the operator may then open the drawer and remove the desired items, e.g., towels, from the warming drawer 10. The operator may then press the on/off switch to turn off the warming drawer 10.

Turning now generally to FIGS. 14-49E, according to the illustrated embodiments there is disclosed a warming apparatus (shown and described as a warmer drawer 112) controlled by an electronic control system to provide improved chamber temperature control, rapid heat-up, improved temperature set point repeatability and minimal temperature variation from a desired set point. The electronic control system of the warmer drawer is shown to interface with (among others) a detection system having various sensors (e.g., temperature, humidity, infrared, scanners, electrical current, microwave, etc.), a heating element(s), a ventilation system, a display device and a user interface to enable a wide variety of desirable and advantageous features. For example, the warmer drawer is shown as a modular device that is adaptable for use in a wide variety of locations and environments and with other appliances, fixtures or structures. The warmer drawer (when in use) is intended to use a continuously adjustable amount of power in a heating element to maintain a more precise control of temperature within the chamber (rather than conventional and less-precise “on-off” type devices, however, the electronic control system could be configured for use with conventional heating elements and sensors to reduce swings in temperature). The warmer drawer is also shown to include a ventilation system that may be actuated by various technologies to regulate the flow of air, heat and/or moisture throughout the chamber. The ventilation system may include a heating element and/or fan within the chamber, or a heating element and/or fan may be located remotely from the warming drawer and fluidly interconnected by a suitable passage or duct. The warmer drawer is also shown to include a display device configured to display information to a user related to operation, temperature, functions, times or other control parameters for the warmer drawer. The display device is configured to display text (stationary or scrolling) and graphic images or illustrations. The warmer drawer is also shown to include a user interface (locally controlled and/or remote-controlled) to facilitate operation (e.g. selection of inputs, setting changes, start, stop, hold, etc.) of the warmer device by a user. The warmer drawer is further shown to have a temperature-controlled internal chamber that is accessible by access through a door or panel (e.g. “reach-in” etc.) or by a movable portion (e.g. movable holder, extendable portion tray, panel, drawer, etc. configured to hold objects within the temperature controlled environment of the chamber) that is extendable from, and retractable to, the chamber (in a manually-operated or power-operated manner). The warmer drawer is also capable of use in attaining and maintaining a desired temperature(s) for a wide variety of objects including foods (and other non-food items (e.g. plates, towels, etc.). The warming drawer as shown and described may also be constructed as a multi-use drawer (e.g. for warming, drying, baking, boiling, steaming, roasting, etc. and also for cooling). The ability to combine a warmer drawer with an appliance such as range, a mini-oven, a toaster oven, a steam drawer, a baking drawer, a boiling oven, a broiling oven, and a microwave oven thus reducing the space required and the ability to multi task from one appliance. This ability to combine a warmer drawer with an appliance or an appliance combined with a warmer drawer provides the user with advantages in space, reduce energy usage, and time savings. Accordingly, all such features are within the scope of this disclosure. However, this description is not intended to be limiting and any variations of the subject matter shown and described may be made by those of ordinary skill in the art and are intended to be within the scope of this disclosure.

FIGS. 14-17 illustrate an exemplary embodiment of a warming apparatus shown as a warmer drawer 112 that includes a cabinet 114 (e.g. case, box, enclosure, etc.) having walls, a top, and a bottom that define a chamber 116 (e.g. cavity, compartment, etc.) within the inside of the cabinet 114. The cabinet also includes an external shroud (e.g. the wrapper bottom/back) surrounding the walls, top and bottom to define the outer surface of the cabinet. Air or insulation is provided within the space between outer surface of the cabinet and the chamber wall inside the cabinet and is intended to provide improved heat loss control when using such a two-wall type construction. The use of only an inner chamber can be used as long as the surrounding surfaces are configured to withstand or accommodate the heat loss. The inner chamber is composed of a chamber bottom and sides, chamber top and sides make up the full inner chamber. A face plate (e.g. panel, door, etc.) provides the connection for the inner chamber and the outer surface of the cabinet to the front of the warmer drawer. Note here that there are many ways to construct a cabinet for a warmer drawer, which may include any number of layers from the inside chamber wall to the outside surface. This writing describes only two of the many ways for construction of a warmer drawer, but is intended to include all such constructions. According to other embodiments, the warmer drawer may consist of multiple warming cavities or compartments in the same appliance. Further, the chamber can be expanded and configured for quantity of items or containment of specific items. For example, the cabinet 114 can be expanded horizontally or vertically, also the warmer drawer may have various mounting locations in relation to another appliance (see FIG. 28 for example).

The warmer drawer 112 is also shown to include a heating system 120. The heating system is shown to include one or more heating elements 122 within the chamber 116 (shown for example as one heating element 122 within the chamber 116 in FIG. 16). The heating system 120 may also comprise one or more heating elements 124 in connection with the ventilation system 130 where the heating element(s) 124 are shown integrated with an airflow device (e.g. fan 132, etc.) located within the chamber 116 or external to the chamber 116 (see FIGS. 18, 19 and 40 for example). The heating element 122 is shown schematically in FIG. 16 as a cal rod (i.e. sheathed heating element) design that is used presently in many conventional warmer drawers. However, there are a number of alternative heating elements or technologies that can replace or supplement a standard, single cal rod type heating element. For example, such heating elements include (but are not limited to) convection heater(s); axial fan heaters, (having an integrated heating element and a fan); wire heating element(s); heat plate(s); thermal ceramic heater(s); flexible heater(s) which are also called thin film heating elements. The flexible heaters can be formed and bent into any shape. Other heating elements include: light(s); inductive heater; heat pump type which can provide heating and cooling (for applications involving a heating apparatus that can also provide cooling); warming liquids; sonic; heat exchanger, electromagnetic energy such as infrared heaters, radio frequency, gas, solid fuel products and microwave. These heating elements can be placed not only on the bottom of the chamber (as shown for example in FIG. 16) but also on the walls, on the top, front, and in the back of a warmer drawer or any combination of surfaces. Using these heating elements are intended to improve the heat control and accuracy of the temperature achieving even temperatures throughout the inside cavity. According to alternative embodiments, the use of two cal rods (or other suitable heating elements) can be used to improve upon the temperature(s) within a cavity and to further reduce pre-heat/start-up times. The use of electronic(s) and different heating elements can greatly improve on the start-up times reaching set temperatures faster. Likewise, pre-heat times, to stabilize the temperature inside the cavity, are reduced with the use of a heater or heaters listed above. Greater control means less over and under shoots resulting in better temperature holding capability. Greater versatility can be obtained with the use of electronic control and the different types of heating elements. According to other alternative embodiments, the heating elements may be configured to provide other thermal functions within the chamber (in addition to warming) such as baking, broiling, boiling, steaming, roasting, rotisserie, etc. and may include other suitable heating elements such as a microwave heating element, infrared heaters, etc. According to another alternative embodiment, a heating element may be made from a thermoceramic conductive coating having a geometric heat radiating pattern formed thereon to suit the particular geometry of the chamber.

The ability to better regulate the electrical current to the heating elements 122, 124 such that the power output can be increased or reduced with improved accuracy, and similarly increasing or decreasing the heat output to the chamber 116 with greater accuracy is achievable with electronic control. An electronic control system 140 for a warmer drawer 112 is shown, for example, in FIGS. 18, 21 and 22 and is intended for operation with AC or DC power supplies and is configured to regulate the amount of electrical power (e.g. current and/or voltage, etc.) to the heating elements 122, 124, and to control the speed of a variable speed fan 132, 134 and the position of a damper 136 (which may all be located at the warmer drawer or remotely from the warmer drawer) in the ventilation system, based upon input signals received from a detection system 150 variety of sensors located at suitable locations within (or external to) the chamber 116 (shown for example as a temperature sensor 152, a humidity sensor 154, an IR sensor 156, etc.). The electronic control system is also shown to interface with a display device 160 for presenting information to a user that is representative of the operation, temperature, time, function, performance or other suitable parameters of the warmer drawer or its constituent components. The electronic control system 140 is also shown to interact with a user interface 170 (which may be remotely controlled or locally controlled) that is intended to permit a user to directly input (or change existing inputs) such as time, temperature, etc.). Accordingly, the electronic control system 140 is intended to enable a wide variety of new features/functions for the warmer drawer 112 and to provide an improvement over conventional products that cycle electrical current off and on (i.e. which have the elements provide full heat power “on” and then complete heat power “off” in attempt to reach and maintain a desired temperature. The electronically controlled warmer drawer 112 can determine the needed heat load for the chamber 116 (e.g. based on settings established by a user at the user interface 170 and/or input signals received from suitable sensors) and supply only that amount of heat, thereby minimizing over shoots with quick warm-ups and regulation of electricity and heat when approaching and attaining the desired set point.

According to an exemplary embodiment, the electronic control system 140 includes a positive temperature coefficient of resistance (PTC) current/voltage controller for controlling the heat and power requirements and providing rapid response during start-up. This PTC controller allows current to the heating element(s) 122, 124 and as temperature gets close to the upper limit, the PTC device limits the current to the heating element, stopping the rapid rate of heat/temperature increase in the chamber 116, thus preventing overshoot. PTC thermistors (thermally sensitive resistors) are solid state, electronic devices, which detect thermal environmental changes for use in temperature measurement, control and compensation circuitry and exhibit an increase in electrical resistance when subjected to an increase in body temperature. PTC devices remain in their low resistance state at all temperatures below the temperature corresponding to the desired set point. When the temperature corresponding to the desired set point is reached or exceeded, the PTC exhibits a rapid increase in resistance thereby quickly limiting current to the heating element circuitry to minimize temperature overshoot. Once the temperature within the chamber decreases to a normal operating level, the device resets to its low resistance state providing full load current to the heating element. The dramatic rise in resistance of a PTC Thermistor at the transition temperature tends to makes it an attractive candidate for current limiting applications. For currents below the limiting current, the power being generated in the unit is not sufficient to heat the PTC to its transition temperatures. However, when abnormally high fault currents flow, the resistance of the PTC increases at such a rapid rate that any increase in power dissipation results in a reduction in current. These devices have a resistance temperature characteristic that exhibits a very small negative temperature coefficient until the device reaches a critical temperature for the upper limit or set point of the warmer drawer, which is referred to as the “curie”, switch, or transition temperature. As this critical temperature is approached, the PTC device begins to exhibit a rising positive temperature coefficient of resistance as well as a large increase in resistance. This resistance change can be as much as several orders of magnitude within a temperature span of a few degrees. Thus as the cavity chamber temperature increases from an ambient temperature, the PTC electronic device increases in surface temperature reducing the ability to dissipate heat which results in an increase in resistance resulting in reducing the current to the heating element. This increase in resistance and reducing current also slows down the heat up when coming to the set point. These devices also do not completely stop the flow of current to the heating element, but rather, limit the current. Thus providing and maintaining a steady temperature by substantially eliminating on/off swings that other conventional warmer drawers provide. This design also provides users with cost savings; since the undesirable “on/off cycling” with its corresponding overshoots and undershoots is avoided, the full current draw of the heating element is also avoided and the warming drawer uses only the required current for start-up heating and maintaining the desired temperature. According to other embodiments, the electronic control system includes any one or more of a micro controller(s), micro technology, integrated circuits, drivers, and microprocessors that may be mounted on one or more printed circuit boards, to provide the desired functionality of interfacing with the heating elements, the ventilation system, the sensors, the display device, and the user interface.

The illustrated power board and control board show one type of electronic control (see FIGS. 18, 21 (control board) and 22 (power board)). The boards are shown as two boards, but may also be fabricated on the same board. Knobs to interface with the electronics can be provided, thus providing the “look” of a mechanical product. Construction of the electronics in a warmer drawer can use, but is not limited to, high heat construction design, specialized adhesive construction, use of loop resistant circuitry which is designed for use in membrane switches, special edge seal finishing for design of key pads using membrane switches, ESD/EMI/RFI shielding, electronics, and using display technology such as light emitting diodes, liquid crystal display, plasma, dot matrix, vacuum fluorescent display, etc. All of these can improve the control, display, design, look and operation of the electronic(s).

Such embodiment providing and electronic control system as described above is an improvement over prior art methods of cycling power on and off in an attempt to control the heat. With the improved method one can determine the needed heat load for the chamber and supply only that amount of power/heat. This also can prevent temperature over shoots by quick warm ups and when almost reaching the fixed set point, limit the amount of energy heat (current) when reaching the fixed set point. The ability to better regulate the electrical current to the heating elements such that the power output can be regulated will improve accuracy, and similarly increase or decrease the heat output to the chamber with greater accuracy. This innovation reduces the user's cost to operate this product. The electronics and sensors can determine the needed heat load for the chamber and supply only that amount of heat to the chamber.

The warmer drawer 112 also includes a display device 160 (see FIG. 35A, shown for example as integrated with a user interface 170) that provides the ability to display to the user the operations, functions, temperatures, times and other features (e.g. fan speeds, alarm controls and signals, clock displays, message board-type displays, etc.) and may be provided in text (in any suitable language) or with suitable images (e.g. pictures, pictograms, graphics, animation, etc.—such as a spinning fan, an image of a food product such as a fish, chicken, beef, etc.) using electronics to convey information to the user for accurately controlling operation of the warmer drawer 112 to advance the ability to cook and hold desired temperature(s). The display device 60 may include one or more display panels 162 (such as three or four LED display panels for providing numeric or text information (e.g., in a stationary or “scrolling” manner, etc.)). One or more of the display panels on the display device may also be configured as an LCD, plasma, dot matrix, vacuum fluorescent or other suitable type of display panels (in one or more colors and with varying degrees of illumination to adapt to background lighting) for conveying text, graphics or other desirable images to a user.

The warming drawer 112 also includes a user interface 170 (see FIGS. 35A-E, shown for example as integrated with a display device 160) shown as an electronic touch control panel 172 (e.g. touch pad, key pad, input device, etc.) according to an exemplary embodiment. The user interface 170 may include any suitable input elements 174 (shown by way of example in FIG. 35A as ON/OFF, ADJUST (increase and decrease) and PRESETS: HIGH, MEDIUM, LOW, PROOF, BAKE, BROIL; and by further way of example in FIG. 35B as POWER ON/OFF; TIME-SELECT; TEMPERATURE-SELECT), for selection and input of desired operations by a user, however any suitable input elements may be used to suit a particular application. According to any exemplary embodiment, the user interface 170 may be provided using any suitable technology such as (but not limited to) a piezo touch panel, or a capacitance electronic touch control panel (e.g. made of glass, metal or plastic, etc.) with selection of the operating function(s) made by touching the surface of the glass, metal, or plastic to operate any size warmer drawer/multi-use drawer could be used. In addition, tactile (membrane switches) touch control panel switch pad(s) for a 29.99″ and smaller warmer drawer/multi-use drawer for touch controlling the operations of a warmer drawer could be used. Tactile (membrane switches) touch control panel switch(s) for 30.01″ and larger warmer drawers for touch controlling the operations of a warmer drawer could be used. For any size warming drawer, other types of user interfaces may include resistance type touch control keypad (whereby touching plastic, metal, glass, etc.) at a location causes a change in an electrical signal to be measured and the electronic control system responds to this change). According to any exemplary embodiment, the user interface may include use of membrane switches, piezo, capacitance, paddles touch soft switch technology, paddles touch digital encoder (micro-encoder), capacitive, infrared, high frequency, magnetic, field effect, charge transfer, hall technology resistance, and inductive. Further, the face panel of the user interface can be fitted with decorative overlays, underlays, labels, trim, and completed control panel assemblies. Touch control keypad(s) panels 172 can be installed flush (see FIG. 35D), raised (see FIG. 35E), or recessed (see FIG. 35C) for use in connection with the electronic control system. Further, the touch control key pad(s) 172 of the user interface 170 can be installed in any plane of the warmer drawer 112 (or remote structure when operated by remote control) with the use of electronics. According to an alternative embodiment, the display device and the user interface may be arranged as separate (yet still intercommunicating) devices at any suitable location on the warmer drawer.

Electronic controls can be placed on any surface to accommodate any design or for matching or simulating the look of other products that may be associated with the warmer drawer. The touch control keypad(s) 172 of the user interface 170 and display(s) 162 of the display device 160 can be placed on the front of a warmer drawer 112 to provide the user with “instant viewing” of the operations and functions without having to open up the warmer drawer. Touch control panels 172 can be made of metal, plastic or glass to suit a particular application. The use of micro controller(s), integrated circuits and drivers, PC board(s), processor, and power, and other electronics can be used in the electronic control system 140 to interface with the touch pads 172 of the user interface 170 to control operation of the warmer drawer 112. Any size from a small to a large warmer drawer can be fitted for use with a touch type control pad (e.g. piezo, capacitance, resistance, etc.). Further, any size from a small to a large warmer drawer can be fitted for use with an induction touch control pad. The design of the electronics can be unique or matched to the other looks, aesthetics, appearance or decor on adjacent or cooperating appliances or structures. The overall size, design, look and feel of a warmer drawer can be matched to the size, design, look and feel of any appliance or structure.

According to an exemplary embodiment, the touch control panels 172 of the user interface 170 can be remotely controlled having the electronics, or a portion of the electronics, located not on the product but in a different location not on the warmer drawer (see FIG. 36). Remote control can be by wire or by wireless controlling the functions of a warmer drawer. The touch control panels 172 of the user interface 170 may have graphic(s) (e.g., pictographs that are unique or specific to the design for the matching product(s) or specific to the required designs and functions, etc.). The use of electronic provides the user with better control and offers more flexible operations than can be obtained with a conventional mechanical control system. With this flexibility the user can perceive (e.g., see, hear, etc.) what is happening and can modify the function of the warmer drawer to achieve a desired performance.

The structures for the display device 160 and the user interface 170 control functions could be mounted to the fixed faceplate or the movable face/door of a warmer drawer (see FIGS. 35C-35E and 37). With the display device 160 and/or user interface 170 mounted on the face panel with the warmer drawer closed, viewing of the display device and user interface can be an indicator of the operations inside the chamber 116. In applications where the electronics are mounted on the face panel of the warmer drawer 112, the electronics can be disconnected when the drawer is pulled out thereby disconnecting functions. Disconnection can be accomplished by wireless communication or by a wired system. Wires of suitable length can be provided so as not to disconnect operations and interfere with the operation of the drawer being opened.

According to another exemplary embodiment, the display device 160 and/or user interface 170 may be placed on any desired surface of the warmer drawer or associated structure (e.g., to accommodate any design for matching or simulating the look of other products the appliance may be paired with, or to protect the components from damage, or exposure to adverse environments, etc.). By way of example, the display device 160 and user interface 170 may integrated (shown for example as an integrated display/interface 179; however, the display and interface may be kept as separate devices) and/or arranged to be “hidden” from normal view with a panel, for example, by the closing of a sliding panel (which may be spring-biased) or by integrating the display/interface 179 with a rotating panel or L-shaped plate (shown for example as a rotating drum 176 in FIGS. 49A-49E) which may be mounted on a stationary portion 114 of the warmer drawer or on the extendable portion 118 (e.g., movable holder, etc.) and repositionable in a variety of orientations for ease of viewing/operation and for concealment. This ability to conceal the display/interface, to protect it from damage, or match other looks, and having it independent of the moving drawer but still have a flush looking front from two parts, or to provide a smooth looking front is intended to enhance the functionality and options available to a user for operation of the warmer drawer. Once the user has completed viewing the display or operating the interface, the user (or the warmer drawer itself) can rotate the drum to a position to conceal the display/interface and expose a “matching” panel 177 to provide a smooth-looking or substantially uniform front appearance. According to one embodiment, electronic sensors may be provided in the display/interface so that the user can touch the front of the display/interface for movement to a storage position or for movement to a viewing/operating position. When the electronic sensors in the display/interface sense the “touch”, the rotation begins until reaching the stop point (e.g., at the next “position” of the display/interface), such as the display/interface panel provides the smooth front. Another way the display/interface may be moved to the storage position is if the warmer drawer (or another associated appliance) has been “off” for a predetermined time period. Once such a predetermined time period has elapsed, the display/interface may automatically move from the viewing/operating position to the storage position. A drive device such as a motor or actuator (shown, for example, as a drive motor 178 in connection with the display/interface 179 in FIG. 48; however, other suitable devices for rotating the display assembly can be used to provide movement) is provided for operation of the repositionable display/interface. Suitable devices such as switches, stepper motor(s), magnetism, or a positive stop like metal can be used for the location of “stop points” for locating the desired positions of the display/interface.

According to another embodiment shown for example in FIGS. 19 and 20, the warmer drawer includes a fan 132, 134 (with or without a heating element 124 attached to the fan, and shown as an axial fan 132 with heating element 124 in FIG. 19 and a cross blower 34 with heating element 124 in FIG. 20) that is secured to the inside of the chamber or located remote but in fluid communication with the chamber (e.g. by a duct 137 etc.—see FIG. 40 for example) to circulate the heated air and that interfaces with the electronic control system 140 to receive its control and electrical power. The illustrated fan configurations are intended to provide improved heat control and response time by improving the uniformity of the temperature within the chamber 116 and minimizing layering, stratification or other gradients (i.e. not necessarily for convention cooking purposes). With the slowly circulating air, “hot spots” are substantially eliminated within the chamber 116. Also, slow moving air generally will not adversely affect the hold quality of the object(s) in the chamber 116, but will improve upon it because the temperature over and under shoots are substantially eliminated. Accordingly, chamber temperature management is also improved by ventilation control to substantially eliminate temperature gradients, large temperature swings and reducing pre-heat/start-up time within the chamber. A fan or other device for moving air (or otherwise providing air movement within the chamber) is also intended to provide humidity control within the chamber 116. Humidity build-up in the chamber 116 can be controlled by providing a vent system with controlled variable size openings, such as a powered vent system (see FIGS. 23A-26). Having a variable speed fan/motor associated with a vent with variable size openings for moving air in and out, and mounted inside the chamber 116 or mounted outside the chamber 16 is intended to provide different air flows as needed to control (e.g., increase, decrease, maintain, etc.) moisture accumulation and/or temperature differences with the ability of introducing fresh air in the chamber 116. A fan moving the air can provide “mixing” and substantially prevent front to back, side to side, or top to bottom temperature differences. The resulting air movement by a fixed or a variable speed fan is intended to hold a uniform temperature throughout the chamber. The fan 132, 134 can also be used for ducting heated air or moisture out of the chamber 116 of the drawer 112. Another aspect of this design is the ability for the fan 132, 134 to be controlled by a humidity sensor 154 in cooperation with the electronic control system (see FIG. 18). This can improve the quality of the food or non-food items being held in the chamber 116.

According to the embodiment illustrated in FIGS. 23A-23B, the vent with variable openings includes a damper 136 or louver(s) configured to co-act with apertures 138 (e.g., holes, slotted openings, etc.) to provide ambient air inlet(s) or exhaust passageways, that can be variably positioned between “opened” (as shown in FIG. 23A) and “closed” or at a partially opened position therebetween either manually or by an actuator 139. According to a preferred embodiment, the vent system 130 includes a sliding damper 136 that interacts with the apertures 138 and is driven by an actuator 139 that receives a suitable signal from the electronic control system 140. For example, the actuator 139 may be configured as a motor-driven drive screw (see FIG. 24), or a motor driven slide/rack and pinion device (see FIG. 25), or a solenoid operated device (see FIG. 26), or bimetallic device, or an electromagnetic device, or other suitable electronically or electro-mechanically controlled device for adjusting the position of the damper 36 in relation to the apertures 138. The ability to control the flow of air and moisture within the chamber 116 by an actuator 139 coupled to a damper-vent apparatus is intended to regulate the flow of air being exhausted from, or brought in to, the chamber 116 of the warmer drawer 112. This controls the loss of moisture (humidity) or the ability to hold moisture inside the chamber. The air inlet(s) or outlet(s) can be opened immediately all the way (full open) or closed all the way (sealed chamber) or opened to a preselected position to control heat or moisture build-up. The size of the air inlets/outlets through the vent apertures 138 may also be modulated based upon a suitable signal from the electronic control system 140 (such as in response to a signal representative of a humidity level or signal from the humidity sensor 154). With the use of a forced air (powered) or circulating air system, even greater control can be had with a power venting system. The damper (e.g., louver, slide, etc.) allows for flows to be proportional thus controlling air movement and heat. Vent apertures 138 can be located at any suitable place such as in the front or face panel of the warmer drawer 112, at the side top and/or at the bottom, or any other suitable location to achieve a desired air flow pattern within the chamber 116. The warmer drawer 112 can be configured with any venting configuration which will permit air to leave or enter the chamber 116. Any suitable and connected actuator 139, for example, a motor, that can provide motion, which can be transformed into movement for closing or opening the vents, can be utilized. A humidity sensor 154, including associated electronics, can detect and provide control to the vent fan 132,134, and heater 122, 124. Such device can also be configured to provide user input (e.g. through the user interface) for setting the desired humidity level inside the chamber.

According to another embodiment the warmer drawer 112 may be configured as a multi-use-warmer drawer that combines a mini-oven, warmer drawer/broiling cavity, multi-use warmer drawer/steam oven, multi-use warmer drawer/baking oven and multi-use warmer drawer/microwave oven in any suitable combination. Combining the warmer drawer with other heating or cooking products can reduce space used in a kitchen (institutional, commercial, residential, etc.). Using these warmer drawer/multi-use drawers can save electricity and heat energy due to their small size. A large portion of the energy consumed in cooking applications is often associated with preparation of small amounts of food. Having to heat up a large oven takes time and is more expensive than using a mini-oven/warmer drawer. This mini-oven/warmer drawer could take the place of a toaster oven saving counter space. When combined with a broiling element within the chamber 116, additional capabilities for cooking and providing temperature holding capabilities may be realized that are not presently found in conventional products. Another embodiment provides a “multiple use” warmer drawer/mini-oven/broiling cavity. It is readily apparent from the above description that combining the warmer drawer 112 as described herein with other cooking equipment can be a great benefit to a home kitchen or other food preparation or maintenance location. It also readily apparent from the disclosure that any desirable appliance with a warmer drawer.

According to another embodiment, a warmer drawer 112 or multi-use drawer can be configured as a modular unit having the ability to be adapted to “fit” into a range or other appliance(s) without being built-in (see FIGS. 24 and 28 for example). A modular warmer drawer 112 or multi-use drawer can be operated independently from the other appliance with which it is associated. For example, the lower storage drawer 182 of an oven/freestanding range 180 can be removed and replaced with a modular unit 112 in its place to provide cooking space and food holding capability. This warmer drawer 112 or multi-use drawer would operate independently of the freestanding range 180.

According to another embodiment the warmer drawer 112 is adaptable as a warmer drawer/multi-use drawer shown for example as a mobile pedestal heated chamber with drawers, slides, or doors for warming, cooking and holding food and non-food applications (see FIGS. 29-30). The warmer drawer/multi-use drawer is shown for example as combined with a mobile pedestal 184 to provide a heated chamber apparatus that is shown as not built into a wall, cabinetry, structural member, immovable island or other non-mobile structure. A warmer drawer/multi-use drawer having a heated chamber, accessible by doors, drawers, lids, or the like is configured to rest on the floor or on other surfaces and be freestanding on its own. The warmer drawer/multi-use drawer or its pedestal 184 is intended to be self-supporting and rests upon its own structure (shown for example as footpads, foot pegs, legs, wheels or casters, etc.). A structure attachment can be made directly to the warmer drawer/multi-use drawer or to a mobile frame 186, upon which the warmer drawer/multi-use drawer is supported. The structure attachment can be removed when not in use or it can be permanently attached. The warmer drawer/multi-use drawer can be removed and placed on any desired surface for use and then returned to the structure attachment, or the warmer drawer/multi-use drawer may remain coupled to its pedestal 184 and immobilized during use (e.g. by wheel locks, chocks, etc.). The mobile frame can be made of wood, metal, plastic, composite material or any combination of such materials intended to provide a lightweight yet sturdy support and transport structure. Another embodiment of the warmer drawer/multi-use drawer can provide for use indoors or outdoors, such as by weather-resistant features (e.g. sealed touch pads, electronic modules, gasketed door panels, etc.).

A mobile heated warmer drawer/multi-use drawer can also be installed into a mobile island or cart 187 to be used for cooking and holding food (and for non-food applications as well) (see FIG. 29 for example). Such a mobile warmer drawer, island or cart can be equipped with a cutting/work surface top made from metal, wood, solid surface materials, or other materials. The top can be a fixed cutting/work surface or made removable for remote working/cleaning/serving or replacement. According to any exemplary embodiment, the warmer drawer/multi-use drawer as shown and described (e.g. mobile or stationary, etc.) may be used in any desirable location for any suitable application. For example, the warmer drawer/multi-use drawer may be used in kitchens (institutional, commercial or residential) for food items and non-food items, and may also be used in eating or serving areas or devices (e.g. caterers, buffets, picnics, lunch-carts or trailers, etc.) or may be used in other applications such as hotels, resorts, spas, golf courses, cruise ships where it is desirable to maintain the temperature of objects (such as food objects and non-food objects) for the comfort or convenience of users, customers, consumers, guests, staff, etc.

According to another embodiment, a warmer drawer/multi-use drawer 112 is provided that is configured to be controlled by the electronic control system 140 and equipped with an AC or DC electronic temperature sensor 152 located inside the chamber 116 such that the temperature of the chamber 116 can be detected accurately. Controlled by electronics and equipped with an AC or DC electronic temperature sensor 152 provides control and operation response, to sense temperatures in the chamber 116 and then the electronic control system 40 provides a suitable output to control the heating element(s) 122, 124 functions for on/off or regulated power operation. Any electronic sensor used for detecting temperature, resistance, or power using such devices as thermos/thermal detection device(s) for the control of the chamber temperature can be used with the electronic system in a warmer drawer/multi-use drawer. The heating element is electronically connected to a temperature-sensing device and is AC or DC powered in accordance with requirements for the warmer drawer installation or use location. With user selected settings (e.g. through the user interface 170) or preset (factory or otherwise) settings of the electronic control system 140, the signals associated with maintaining the desired temperature(s) within the chamber 116 are sensed and sent by the temperature-sensing device 152 within a predetermined desired range of operating temperature(s) or set point(s). The sensor 152 can be mounted on the electronic board or it can be attached by itself to any wall or location in which detection of the temperature can be made. The ability to better detect the temperature within the chamber improves the response time to the changes inside the chamber and improves the accuracy of the actual temperature in the chamber when compared to the desired set point. This quick response and control reduces the effects of overshoot and undershoot. Any electronic, mechanical, or electromechanical sensor can be used for detecting temperature, resistance, or power for detection and control of the temperature in the chamber with the use of electronics. Any electronic, mechanical, or electromechanical, AC or DC sensor can be used for detecting and control of temperature, resistance, or power for better control of the chamber temperature. Such sensing or detecting devices, which can be used include, but are not limited to temperature sensors, thermostats, thermal, temperature controls, thermal protectors, thermal cutoffs, thermal switch, thermocouples, adjustable thermostats, printed circuit board thermostats, hermetically sealed, time delay relay, bulb and capillary, cold controls, electronic controls, bimetallic, pressure switches, creep action thermostats, resistance temperature detectors, controllers, manual reset, automatic reset, disc thermostat, snap action switch, negative temperature coefficient of resistance thermistors, power positive temperature coefficient of resistance thermistors that can be controlled by electronics, or other suitable device. The sensing devices, along with the electronic control system is intended to provide better temperature control of objects within the chamber and ultimately, improved user satisfaction.

According to another embodiment, sensing technology such as scanner detection technology may be used to directly sense the temperature of an object in the chamber for providing a signal to the electronic control system for controlling the power and heat from the heating element and/or controlling operation of the ventilation system 130. A warmer drawer 112 can have the ability to detect objects placed inside the chamber 116 and then set temperature(s) for maintaining required temperature. For example, in a warmer drawer with item detection on a target surface, an IR sensor 156 collects a small amount of energy (usually 0.0001 watt) radiated from the target, generates an electrical signal that is amplified by a precision amplifier and converted into voltage output. A CPU digitizes the signal by an Analog-to-Digital Converter, an Arithmetic Unit solves a temperature equation based on Planck's Radiation Law, compensates for the ambient temperature and emissivity resulting in a temperature reading within a fraction of a second after user places the item in the field. Using this technology one can measure the temperature of an item or cover the complete surface from a five (5) meter distance as long as the Field of View is filled by the target. Also, many IR sensors measure in the 8 um to 15 um wavelength band where the atmosphere is almost totally transparent. IR sensors can operate in complete darkness. In the 8 um to 15 um wavelength band, IR can penetrate PE film (for example: a plastic trash bag or saran wrap). The IR thermometer sensor 156 can detect the presence of the object.

IR sensing can measure objects that move, rotate, or vibrate (e.g., web process or any moving process). They are understood not to damage or contaminate the surface of the object of interest. They measure the temperature of the actual product being used in a warmer drawer and not some of the other parts of the surfaces. Thermal conductivity of the object being measured such as glass, metal, wood or even very thin objects does not present a problem, as is the case with certain other sensors. Response time is typically in the millisecond range, which gives the user more information per time period. The IR detector system can be used for heat/fire and/or distance in the warmer drawer. The use of thermal sensing technology such as RTDs (resistance temperature detectors), integrated circuit sensors (IC), thermistors, IR thermometers, bimetallic, and thermocouples can also be used. Other sensors like photoelectric, photon, optics, indium-gallium-arsenide, and thermal detector could be used in place of IR for the detection of items placed on the surface.

Another embodiment provides a warmer drawer/multi-use drawer configured for outdoor locations having the ability to weather typical outdoor temperatures and environments. The use of electronics for warmer drawer/multi-use drawer can provide better sealing for use in these environments. With the use of remote locations for the electronic controls when the drawer 112 is used outdoors, the effects of the environment on the controls is minimized. Electronics are typically not subject to mechanical problems of “turning force” due to cold temperatures in certain locations. They are usually resistant to environmental conditions and problems to an extent unlike mechanical controls and switches, which can develop rusting or dust build-up for example. The electronic controls are also usually not subject to cleaning problems, as are mechanical controls. Electronic controls can be best suited for outdoor applications where extreme temperatures and weather conditions exist, because they typically have no (or minimal) mechanical moving parts to fail.

Another embodiment provides for the use of aromatic materials 190 such as favoring additives, e.g. wood clips, liquid smoke, etc.) or fragrances that can be added into a receptacle 192 within the chamber 116 to impart flavoring to food objects or desirable fragrances to non-food objects inside the chamber of the warmer drawer (see FIG. 43 for example). This can be accomplished by a receptacle 192 such as a special pan in contact with the heating element 122 or by evaporation, or flavor adding can be accomplished by venting or ducting from a different chamber or outside the chamber.

According to another embodiment, the chamber 16 of the warmer drawer/multi-use drawer 112 may be illuminated when the drawer is opened or when a switch is turned on (see FIGS. 31-34 for example). FIG. 32 illustrates one example of a door-actuated switch 196. FIG. 33 illustrates one example of an electronic sensor 193. FIG. 34 illustrates one example of a mechanical (e.g. rocker, etc.) switch 198. Because the extendable and retractable drawers may be positioned low to the ground and with a small opening, it is sometimes hard to see inside the chamber in certain applications. The use of a light 194 to illuminate the inside is of great help when trying to view the food or other objects without opening the drawer fully. The door or face panel of the cabinet can be provided with a viewing window, and a transparent shelf or pan can also be provided to increase visibility into the chamber.

According to another embodiment, the warmer drawer/multi-use drawer 112 may be configured for use through the electronic control system 140 to provide programmable set point(s), programmable set time(s) and programmable set operation(s) as well as multiples of set time(s), function(s), set points, operations or power on/off, by suitable interaction with the user interface. The ability to select multiple functions, operations and times gives the warmer drawer/multi-use drawer advantages over non-electronic controlled units. Timed on/off control can provide the ability to control the on/off time of the drawer. On/off time(s) can be infinitely set with the use of electronics. This programmability provides the advantage of being able to enter different functions or operations (e.g. more than one, etc.) into the electronic control system and have the warmer drawer/multi-use drawer control all desired functions, an advantage over mechanical or single function units. One can have one, two or more functions, operation(s), set point(s) with substantially limitless programming for control of these events. For example, one may start out with one temperature, at high temperature such as 200 degrees F. for one hour and then being able to reduce the temperature to 160 degrees F. for the remaining time. With a single function controlled warmer drawer the operator would typically have to manually reset the temperature. An electronically controlled warmer drawer/multi-use drawer (e.g., dual use drawer/triple use drawer) permits more user freedom.

A timer device, for example a clock, on the display device can also be provided, which can be changed to permit other programmable information to be displayed. Display illumination may also be selectable such that if the drawer is configured to expose the display, the display may serve as a night light or be adjusted for ease of viewing.

Another embodiment provides a warmer drawer/multi-use drawer 112 configured with a hinged door(s) (see FIGS. 46-47 for example). This permits the user to open the drawer by rotating or folding the door out of the way. The door(s) can be hinged rather than fixed, permitting the door(s) to remain in place and having the door(s) out of the way when accessing the contents of the warmer drawer/multi-use drawer. This also permits the user to open the door(s) to view inside the drawer without having to pull out all or some of the contents.

Referring to FIGS. 44-45, a warmer drawer 112 is shown according to an exemplary embodiment having a powered extendable portion 118 (e.g., “servant drawer”—for convenient access for loading or removal of objects from the chamber) having the ability to open or close by the touch of a user or by some signal device so that a user can open or close the warmer drawer without having to pull or push on a handle or the like through the travel range of the extendable portion. Activation of the warmer drawer can be by touching the drawer door, breaking a beam, interrupting a signal, or having a feed back signal to a sensor/detect with no (or minimal) hand held control or contact with the warmer drawer or extendable portion. An activation system is provided to control operation of the extendable portion by interfacing with suitable sensors, the electronic control system 140 and a drive system 199. According to one embodiment, an activation system is shown as a hall sensor 195 and a magnet 197 used to determine the “stop points” and/or “start points” for movement of the extendable portion and initiate signals for opening and/or closing the extendable portion 118 (note that the sensor 195 is shown on the cabinet 114 and the sensor 195 is shown on the extendable portion 118; however, the sensor and magnet may reversed or provided on other suitable structures). For example, when opening of the extendable portion 118 is desired, the activation system receives an input and initiates a drive system 199 and the sensor 195 detects the initial movement of the magnet 197 away from the sensor 195, which may provide a signal to the display system 160 to indicate position of the extendable portion 118 and may also initiate operation of a drive system 199 (if movement of the extendable portion was manually initiated) to move the extendable portion 118 from a closed position to an open position (see FIG. 44). As the extendable portion 118 approaches the open position, another magnet (not shown) may approach the sensor 195, which then initiates a signal (e.g. a stop point) to terminate movement of the extendable portion. Movement of the extendable portion from the open position to the closed position may also operate in a reverse manner. For example, upon activation the drive system moves the extendable portion 118 toward the closed position, which is detected by the sensor as the (second) magnet moves away from the sensor 195 (and initiates operation of the drive system if manually activated) in a closing direction until sensor 195 detects the approach of magnet 197, such that the field of the magnet detected at the sensor indicates that the extendable portion has reached the desired position, such as the closed position (another stop point), which may correspond to any particular position (e.g., compression of a gasket between the extendable portion and the cabinet, etc.). Also, a change in resistance or other suitable indication can be used to determine the stop points. According to the illustrated embodiment in FIG. 44, a motor-driven drive screw system 199 is employed to move the extendable portion 118 open and closed (however, any suitable drive system such as a motor with a wire, cable, pulleys, etc. can be used). According to an alternative embodiment, a switch (or other suitable device such as light-beam sensors, resistive or inductive touch pads, etc.) can be used to operate the extendable portion and may be located on the unit or it can be remotely located for ease of operation and use, and can be operable to energize any suitable drive device for extending and retracting the extendable portion. According to other alternative embodiments, any suitable sensors and signals may be used to initiate opening or closing of the extendable portion, For example, the signal may be a sound, a voice, a noise signal (e.g. clapping or banging, etc.) interrupting a steady state condition; interrupting a beam of visible light or non-visible light; touching a surface which resistance increases or decreases providing a signal to a sensor for activation; force activation by pushing on the door front; and by a remote control signal such as a handheld control using a radio frequency or light beam, cooperating with suitable sensors. These and other methods can be used to activate the drive system for opening and closing the extendable portion 118 of the warmer drawer 112. By providing an activation system cooperating with a drive system responsive to selected stop points and start points, a user has the ability to actuate the extendable portion (e.g., by touch, interruption of a signal, switch operation, etc.), to which the warmer drawer 112 responds by opening and providing access to the extendable portion 118 and chamber 116 without having to manually pull or push the extendable portion throughout its travel range to access the contents. According to another embodiment, the activation system may detect an increase in resistance as the motor of the drive system 199 approaches (or reaches) the stop point and provide an output signal to stop the motor (or reverse the direction of the motor, or other desirable control action). According to a further embodiment, a stepper motor may be provided so that the number of turns can be counted by the activation system to determine the stop point and provide an appropriate output signal to control operation of the extendable portion.

According to another embodiment, the warmer drawer 112 may also be configured to cool (e.g. refrigerate) objects placed in the drawer. For example, a heat pump system may be substituted for the fan and heater (previously described). By further way of example, a magnetic refrigeration device, or may be a thermoelectric heating/cooling module (e.g., a Peltier-type device or module, etc.).

According to any exemplary embodiment, a warming apparatus such as a warmer drawer for use in stationary or mobile applications in any desirable environment is provided with an electronic controller that interfaces with a heating system (having one or more heating elements within the chamber or remote from the chamber, and that receive electrical power in a continuously variable and regulated manner to provide precise temperature control within a chamber), a ventilation system (including an air flow device such as a variable speed fan/motor, and a variably positionable louver/vent device driven by an actuator for air, heat and/or humidity control), a user interface (locally-controlled or remote-controlled) to permit a user to control the operation of the warmer drawer in a simple and convenient manner, and a display device arranged to provide information to a user in the form of alpha-numeric text messages (stationary or scrolling) and/or graphic images. The warmer drawer may be converted to a multi-use drawer by providing suitable elements within the chamber (e.g., for cooling, or for other purposes such as baking, broiling, boiling, steaming, roasting, etc.). The warmer drawer may be installed in any convenient arrangement such as on a mobile pedestal, or supported by a cabinet, such as under a counter, or with a built-in oven as more fully described in a publication entitled Warming Drawer Installation Instructions, 803150/983-0152-000 REV C, 11/04, commercially available from Wolf Appliance Company LLC of Madison, Wis. The warmer drawer may also feature stainless steel construction, ball bearing drawer glides and accessories such as optional drawer fronts and racks for staking objects in the chamber, and may have an automatic shut-off mode, or a preset programming mode, and variable moisture selection operating features as more fully described in a publication entitled Warming Drawer Use & Care Information, 803149/983-0145-000 REV C, 1/04, commercially available from Wolf Appliance Company LLC of Madison, Wis.

The construction and arrangement of the elements of the warming apparatus as shown in the illustrated and other exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, circuit form, type and interaction, use of sensors, etc.) without materially departing from the novel teachings and advantages of the subject matter recited herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the scope of the present inventions.

The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present inventions as expressed in the appended claims.

Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the present invention is not limited thereto. It will be manifest that various additions, modifications, and rearrangements of the features of the present invention may be made without deviating from the spirit and scope of the underlying inventive concept. In addition, the individual components need not be fabricated from the disclosed materials, but could be fabricated from virtually any suitable materials. Moreover, the individual components need not be formed in the disclosed shapes, or assembled in the disclosed configuration, but could be provided in virtually any shape, and assembled in virtually any configuration. Further, although various components as described herein as physically separate modules, it will be manifest that they may be integrated into the apparatus with which they are associated. Furthermore, all the disclosed features of each disclosed embodiment can be combined with, or substituted for, the disclosed features of every other disclosed embodiment except where such features are mutually exclusive.

It is intended that the appended claims cover all such additions, modifications and rearrangements. Expedient embodiments of the present invention are differentiated by the appended claims. 

1. A warmer drawer comprising: a housing having a cavity; an extendable portion slidably connected to the housing, wherein the extendable portion is sized to fit within the cavity; a door connected to the extendable portion; a heating element located in the cavity; a fan for moving heated air within the cavity; electronic controls for operating the fan and the heating element; and a sensor in communication with the electronic controls for controlling a current supplied to the heating element.
 2. The warmer drawer of claim 1 further comprising a panel configured to conceal the electronic controls.
 3. The warmer drawer of claim 2 wherein the panel is one or more selected from a group comprising a sliding panel, a sliding spring-biased panel, a sliding panel display, a panel on a rotating element, an L-shaped plate, a matching panel, and a portion of a rotating element having at least one electronic control thereon.
 4. The warmer drawer of claim 3 further comprising a cabinet wherein the panel is located on at least one extendable portion of the cabinet.
 5. The warmer drawer according to claim 1, wherein the electronic controls comprise programmable on/off settings having automatic shutoff with an infinite setting of the automatic shutoff to disable the automatic shutoff.
 6. The warmer drawer of claim 1 further comprising a receptacle for receiving aromatic materials wherein the aromatic materials are one or more selected from a group consisting of a fragrance source, a flavoring additive, wood chips, and a liquid smoke.
 7. The warmer drawer of claim 1 wherein the heating element is one or more selected from a group consisting of a convection heater, a calrod, a heat plate, a glass film, a thermal ceramic heater, a flexible heater, a light, an infrared device, an inductive device, an electromagnetic device, a radio frequency device, a heat pump, a warming liquid device, a heat exchanger, an axial fan heater, a sonic heater, a gas fuel product, a solid fuel product, a radiant heating device, and a microwave device.
 8. The warmer drawer of claim 1 wherein the electronic controls comprise an electronic display touch control panel having one or more input elements configured to respond to a user input and at least one operating technology of the input elements is one or more selected from a group consisting of a piezo electric, a capacitive, a resistive, and an infrared.
 9. The warmer drawer of claim 1 further comprising at least one of an upper chamber and a lower chamber wherein the fan is located in one or both of the upper chamber and lower chamber.
 10. The warmer drawer of claim 1 wherein the electronic controls are located on at least one of the drawer assembly and the door.
 11. The warmer drawer of claim 10 wherein the electronic controls are configured to be concealed by an overlying panel by moving the drawer assembly to a closed position.
 12. The warmer drawer of claim 10 wherein the electronic controls are located with respect to a plane on at least one of the drawer assembly and the door at a location that is flush, raised, recessed, and recessed beneath one or more of a glass, a plastic, and a composite material.
 13. A method of manufacturing a warmer drawer, comprising steps of: defining an enclosure with a chamber and having an opening; configuring a movable portion to be moved with respect to the chamber; providing a heating element to heat the chamber; configuring a user interface to receive input from a user for controlling operation of the warmer drawer; providing a sensor to sense a signal representative of a temperature of the chamber; and configuring an electronic control system for interfacing with the heating element, the user interface, and the sensor to control a supply of electrical power in a continuous and regulated manner to the heating element during operation of the warmer drawer.
 14. The method of claim 13 further comprising the step of providing a second sensor selected from the group consisting of a humidity sensor and a temperature sensing device.
 15. The method of claim 14 wherein the step of providing the second sensor utilizes a sensor selected from the group consisting of a thermostat, a thermal protector, a thermal cutoff, a thermal switch, a thermocouple, a PCB thermostat, a time delay relay, a bulb and capillary device, a cold control, a bimetallic device, a pressure switch, a resistance temperature detector, a snap action switch, and a thermistor.
 16. The method of claim 13 further comprising the step of connecting the user interface having an electronic display touch control panel configured to provide information to a user.
 17. The method of claim 16 wherein the step of connecting the user interface having the electronic display touch control panel utilizes a display panel having technology selected from the group consisting of light-emitting diodes, a liquid crystal display, a plasma, a dot matrix, and a vacuum fluorescent display.
 18. The method of claim 13 further comprising the step of providing an element configured to hide the user interface.
 19. The method of claim 13 wherein the movable portion is one or more of a lid, a door, and a drawer assembly.
 20. The method of claim 18 wherein the step of providing the element that is configured to hide the user interface is one or more selected from a group comprising a sliding panel, a sliding spring-biased panel, a display that is substantially similar to a surrounding surface, a panel on a rotating element, and a portion of a movable element having at least one electronic control thereon. 